How does hydropower energy asymmetrically affect environmental quality? Evidence from quantile-based econometric estimation

The constant increase in CO2 emissions into the global atmosphere draws the attention of researchers and policymakers to its causes. Renewable energy has grown in popularity since it is less polluting, cheaper, and more effective than traditional energy sources. This research aims to evaluate the asymmetric impact of hydropower energy consumption on environmental quality in the top-10 hydropower energy-consuming countries (China, Canada, Brazil, United States, Russia, Norway, India, Japan, Turkey, and France) by utilizing data for the years 1991 to 2018. Most previous research relied on panel data methodologies to access hydropower energy-environment nexus, neglecting the reality that certain countries have no evidence of such type of linkage individually. On the contrary, the current study employs a novel methodology called "Quantile-on-Quantile (QQ)," which can measure time-series dependence for every economy individually to give worldwide yet economy-specific insights into the asymmetric link between the variables. Except for Turkey, hydropower energy consumption considerably minimizes CO2 emissions in our sample economies at different quantiles. Moreover, the magnitude of asymmetry in the hydropower-environment nexus differs by country, needing additional care and government attention when formulating hydropower and environmental sustainability regulations.